Can I request a pull request and include the scintilla upgraded components alone

Don Ho will not accept updates to Scintilla. He handles all this himself. (I hope v3.7 will be a good candidate for Don Ho to consider; lots of nice features :) )

or include the scintilla components as well in my Lexer Pull request?

Pretty much anything changing something inside the Scintilla directory won’t be accepted. This is mostly due to making sure to not maintain a custom version of Scintilla. It is easiest just to use it as-is and keep all the Scintilla stuff strictly to the Scintilla developers.

Your script is amazing. It should have take a long time to do it.
There is also a scintilla mirror on github https://github.com/mirror/scintilla
What about adding it as a submodule. Wouldn’t it be more convenient ?

Convenient? Maybe.
Wise? Probably not. When any change to a third-party library gets automatically integrated into the this project, the project also automatically inherits the libraries (new/unknown) issues e.g. none backwards compatible changes in its interface.
IMO a controlled/managed update of third-party libraries/tools with regression tests/checks is preferred.